连续倒塌工况下钢管混凝土柱-钢梁外伸端板连接节点受力性能研究

Three CFST column-steel beam joints with long bolts and extended endplate were tested in the scenario of progressive collapse. The load-carrying mechanism and failure mode of the joints are investigated in detail. The assessment for the rotation capacity in anti-collapse design and the equivalent dynamic analysis for the specimens are conducted. The analysis results show that the CFST column-steel beam joints with long bolts and extended endplates behave well in the scenario of anti-collapse.For extended endplate connection, the matching degree between endplate thickness and bolt diameter has effects on the formation and development of catenary mechanism in the connection.Relatively weaker endplate compared to bolt would increase the deformation capacity of the connection and contribute to the development of catenary action.It should be guaranteed that the strength of the joint is not significantly lower than that of the beam.A formula which considers the effects of bolt-group height, endplate thickness and bolt diameter for the rotation limitation of extended endplate joint in the design of anti-collapse is proposed. The method for calculating dynamic increase factor in DoD standard only considers the influence of the bending mechanism of joint.Once the catenary mechanism of joint gets involved in load-carrying, the actual response of joint would gradually become larger than that predicted by the method in DoD standard.